Varghese C. Joshua

Prof. Dr. Varghese C. Joshua


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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24 February 2022 in Mathematics
Verified
Journal Article
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SSSinu Lal T S
Sinu Lal T S
VJVarghese C. Joshua
Varghese C. Joshua
Vladimir VishnevskyVladimir Vishnevsky
Vladimir Vishnevsky
DKDmitry Kozyrev
Dmitry Kozyrev
AKACHYUTHA KRISHNAMOORTHY
ACHYUTHA KRISHNAMOORTHY
The model discussed in this paper provides an efficient mechanism for the selection and allocation of available limited spectra for transmission of heterogeneous data in a network. The data packets (customers), belonging to different classes, arrive according to a batch marked the Markovian arrival process (BMMAP). The inventory considered is of multi-type (different types of channels becoming available) and are generated according to a marked Markovian arrival process (MMAP). The number of distinct types of inventory and that of the customers are the same. Arriving customers are allowed to wait in finite buffers of each category which are reserved for distinct classes of customers except for the most general class, which is provided with an infinite waiting space. The number of servers also equals the number of distinct types of inventory. When items of a particular type arrive in the inventory, the service starts, providing the buffer of customers of the corresponding class is non-empty. The service can be viewed as a selection process with Coxian distributed service times. The system is analyzed using the matrix analytic method and performance measures are obtained. The model is illustrated with suitable numerical examples.

6 February 2023 in Mathematics
Verified
Journal Article
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KMKHAMIS ABDULLAH KHAMIS AL MAQBALI
KHAMIS ABDULLAH KHAMIS AL MAQBALI
VJVarghese C. Joshua
Varghese C. Joshua
AKACHYUTHA KRISHNAMOORTHY
ACHYUTHA KRISHNAMOORTHY
In this paper, we consider a queueing inventory system with batch arrival and batch service processes. Customers arrive in batches of sizes 1,2,…,k, according to a marked compound Poisson process. We call a batch of customers as belonging to j when there are j individual customers in that batch. The service facility has waiting rooms for each category of customers and also a room to serve them. Except for category 1, all other customers have finite waiting rooms. The service room has only a limited number of seats. These seats are arranged in such a fashion that customers belonging to category j have groups of seats, each with j seats for j=1,2,…,k. Customers are taken for service according to the availability of seats designated to each category. A category j customer can be taken for service only if j items are available in the inventory. The service time of customers of category j is exponentially distributed with parameter depending on j for j=1,2,…,k. The number of seats available in the service room for each category of customers is restricted to a finite number. The replenishment for items follows the (s,S) policy: fill up to S at the time of replenishment. Lead time follows an exponential distribution. We analyze the system in the equilibrium state. Performance characteristics are evaluated and a number of numerical illustrations are provided.

3 November 2023 in Annals of Operations Research
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NMNisha Mathew
Nisha Mathew
VJVarghese C. Joshua
Varghese C. Joshua
AKACHYUTHA KRISHNAMOORTHY
ACHYUTHA KRISHNAMOORTHY
AMAgassi Melikov
Agassi Melikov
AMAmbily P Mathew
Ambily P Mathew

2 January 2023 in Mathematics
Verified
Journal Article
Open access
PDF file
KMKHAMIS ABDULLAH KHAMIS AL MAQBALI
KHAMIS ABDULLAH KHAMIS AL MAQBALI
VJVarghese C. Joshua
Varghese C. Joshua
AMAmbily P Mathew
Ambily P Mathew
AKACHYUTHA KRISHNAMOORTHY
ACHYUTHA KRISHNAMOORTHY
In this paper, we consider the batch arrival of customers to a transport station. Customers belonging to each category is considered as a single entity according to a BMMAP. An Erlang clock of order m starts ticking when the transport vessel reaches the station. When the Lth stage of the clock is reached, an order for the next vessel is placed. The lead time for arrival of the vessel follows exponential distribution. There are two types of rooms in this system: the waiting rooms and the service rooms for customers in the transport station and in the vessel, respectively. The waiting room capacity for customers of type 1 is infinite whereas those for customer of type 2,…,k are of finite capacities. The service room capacity Cj for customer type j,j=1,2,…,k is finite. Upon arrival, customers of category j occupy seats designated for that category in the vessel, provided there is at least one vacancy belonging to that category. The total number of vessels with the operator is h*. The service time of each vessel follows exponential distribution with parameter μ. Each group of customers belong to category j searches independently for customers of this category to mobilize passengers when the Erlang clock reaches L1 where L1<L. The search time for customers of category j follows exponential distribution with parameter λj. The stability condition is derived. Some performance measures are estimated.

24 August 2018
Verified
Book Chapter
Closed access
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AKA. Krishnamoorthy
A. Krishnamoorthy
VJVarghese C. Joshua
Varghese C. Joshua
AMAmbily P. Mathew
Ambily P. Mathew

5 August 2018
Verified
Book Chapter
Closed access
PDF file
AMAmbily P. Mathew
Ambily P. Mathew
AKAchyutha Krishnamoorthy
Achyutha Krishnamoorthy
VJVarghese C. Joshua
Varghese C. Joshua